I still recommend trying to reinstalling the game, because something might have gone wrong with the installation progress.

If that doesn't help either, you could also try the Steam version of the game as it's working fine at least on my Windows 7. To get the Steam version you can email us your receipt or just a picture of the game's cd at Support[at]Frozenbyte[dot]com and we'll send you a key. Please also link this thread to your email so we know it's you. I hope this sounds okay.